Highly sensitive and quantitative detection of a minute amount of a detection object substance such as protein and DNA in laboratory tests makes it possible to perform treatment by quickly determining the patient's condition. There is therefore a need for a detection device which can quantitatively measure a minute amount of detection object substance with high sensitivity.
Surface plasmon-field enhanced fluorescence spectroscopy (hereinafter abbreviated as “SPFS”) is known as a method which can detect a detection object substance with high sensitivity (see, for example, PTLS 1 and 2).
PTLS 1 and 2 disclose detection devices which utilize SPFS. In the detection devices disclosed in PTLS 1 and 2, a detection chip including a prism made of a dielectric, a metal film formed on one surface of the prism, and a capturing body (for example antibody) fixed on the metal film is used. When a sample containing a detection object substance is provided on the metal film, the detection object substance is captured by the capturing body (primary reaction). The detection object substance thus captured is further labeled by a fluorescence material (secondary reaction). In this state, when excitation light is applied to the prism through the metal film at an angle at which surface plasmon resonance is caused, localized-field light can be generated on the surface of the metal film. With this localized-field light, the fluorescence material for labelling the captured detection object substance on the metal film is selectively excited, and fluorescence is emitted from the fluorescence material. In the detection devices, the fluorescence is detected to detect the presence or the amount of the detection object sub stance.
In such detection devices utilizing SPFS, it is necessary to use highly sensitive light sensors such as a photomultiplier tube (PMT) and an avalanche photodiode (APD) to quantitatively detect weak fluorescence.